Inhibition of Biofilm Formation and Cell Wall Targeting Activity of Endophytic Nocardiopsis Strain KDCGRAW Isolated From the Indian Sundarbans.

The discovery of new antimicrobials is one of the most crucial approaches to tackling the antimicrobial resistance crisis. Strain KDCGRAW was isolated from the root of Rhizophora apiculata (Garjan tree) from the Bonnie camp subdivision of Sundarbans, West Bengal, India. 16S rRNA gene sequencing analysis revealed that the strain belongs to the genus Nocardiopsis. The strain was subjected to fermentation, and the crude extract was analyzed using GC-MS. The extract inhibited Escherichia coli MTCC 1195 biofilm formation and showed a percentage biofilm remaining of 77.69% for 1/2 MIC, 69.18% for MIC, and 51.56% for 2 MIC, respectively. However, MIC and 2 MIC doses of the extract showed a significant biofilm formation inhibition and the percentage biofilm remaining determined was 51.89% and 43.97%, respectively, as compared to the 1/2 MIC 74.93% against Staphylococcus aureus MTCC 2940. The in silico docking and molecular dynamics study revealed that compound 1 and compound 9 exhibited the best docking energies with the two selected biofilm-associated proteins, achieving binding energies of -6.84 and -7.7 kcal/mol on 5XP0 and 7C7R, respectively. In vivo toxicity analysis using brine shrimp revealed that the extract was nontoxic at all the concentration ranges, namely, 1/2 MIC, MIC, and 2 MIC.